The present invention relates to a three-piece solid golf ball. More particularly, it relates to a three-piece solid golf ball which has both excellent flight performance when hit by a driver or a long iron club or a middle iron club, and good spin performance as the ball easily stops on a green, when hit by a short iron club or approach-shot.
Amateur golfers generally regard flight distance as most important factor for golf balls and preferably use a golf ball having good rebound characteristics and little spin amount, such as a solid golf ball. On the other hand, professional golfers and high level-amateur golfers generally regard controllability or spin performance as most important factor for golf balls, and therefore use a golf ball having high spin performance, which is a performance easily putting spin on a golf ball, such as a thread wound golf ball or a spin type solid golf ball. In the context, the golf balls are classified into two groups, one of which is a high spin type golf ball and the other is a long flight distance type golf ball.
However, in the golf balls which have been hitherto developed, in case where flight distance is made preferential, spin performance is lowered, and in case where spin performance is made preferential, flight distance is adversely lowered. For improving the problem, it is proposed in Japanese Patent Kokai Publication Nos. 239068/1997, 239067/1997 etc. that a hardness of a core of a solid golf ball is adjusted to a proper distribution to improve shot feel when hitting and controllability without damaging the long flight distance inherent to the solid golf ball.
Japanese Patent Kokai Publication No. 239068/1997 suggests a three-piece solid golf ball which comprises a core, an intermediate layer and a cover. The core has a center hardness in JIS-C hardness of not more than 75 and a surface hardness in JIS-C hardness of not more than 85, the surface hardness of the core is higher than the center hardness of the core by 8 to 20, the hardness of the intermediate layer is higher than that of the surface of the core by not less than 5. The hardness of the cover is lower than that of the intermediate layer by not less than 5, and a ratio of dimple area to surface area of the golf ball is not less than 62%.
Japanese Patent Kokai Publication No. 239067/1997 suggests a two-piece solid golf ball which comprises a core and a cover. The core has a surface hardness in JIS-C hardness of not more than 85, a center hardness of the core is lower than the surface hardness of the core by 8 to less than 20. A hardness of from the surface to 5 mm from the surface of the core is lower than a surface hardness of the core by not more than 8. A hardness of the cover is higher than the surface hardness of the core by 1 to 15. A thickness of the cover is 1.5 to 1.95 mm, and a number of dimples is 360 to 450.
In the golf balls of the above publications, the shot feel and controllability are improved, but the rebound characteristics are degraded, which reduces flight distance, because the hardness difference between the center of the core and the surface of the core is large.
It is required by not only amateur golfers but also professional golfers to solve the above problem and to provide a golf ball having longer flight distance and better controllability.
A main object of the present invention is to provide a three-piece solid golf ball which has both excellent flight performance when hit by a driver or a long iron club or a middle iron club, and good spin performance as the ball easily stops on a green, when hit by a short iron club or approach-shot.
According to the present invention, the object described above has been accomplished by adjusting a diameter and hardness distribution of the center, the difference in hardness and specific gravity between the center and intermediate layer and a hardness of the cover to specified ranges, thereby providing a three-piece solid golf ball which has both excellent flight performance when hit by a driver or a long iron club or a middle iron club, and good spin performance as the ball easily stops on a green, when hit by a short iron club or approach-shot.
This object as well as other objects and advantages of the present invention will become apparent to those skilled in the art from the following description with reference to the accompanying drawings.